1. Field of the Invention
The present invention relates generally to Internet client-server applications, and more specifically to guaranteeing network client-server response time while providing a way of putting the client on-hold when the response time temporarily prohibits access to the requested server.
2. Related Art
The importance to the modern economy of rapid information and data exchange cannot be understated. This explains the exponentially increasing popularity of the Internet. The Internet is a world-wide set of interconnected computer networks that can be used to access a growing amount and variety of information electronically.
One method of accessing information on the Internet is known as the World Wide Web (www, or the “web”). The web is a distributed, hypermedia system and functions as a client-server based information presentation system. Information that is intended to be accessible over the web is stored in the form of “pages” on general-purpose computers known as “servers.” Computer users can access a web (or HTML) page using general-purpose computers, referred to as “clients,” by specifying the uniform resource locator (URL) of the page. FIG. 1 is a network block diagram showing a plurality of clients and servers connected to the Internet.
When a client specifies a URL, a part of the URL known as the Domain Name is passed to a domain server (DNS) to be translated to a network address. The network address specifies the Internet protocol (IP) address of the intended or requested server. The client request is passed to the requested server having the network address. This process of how the client request eventually arrives at the requested server is operating in virtual IP mode. In this mode, the address of the requested server is never published and thus not accessible to the client. Here, the server uses the path name in the URL to locate the web page requested by the client. A copy of the web page is then sent to the client for viewing by the user. A second mode, called standard mode, will be briefly described next.
In standard mode, the actual address of the requested server is published. Here, the client's specified URL does not include the Domain Name. Therefore, the request does not go through the DNS to eventually arrive at the requested server.
The client-server paradigm described above has served the Internet well. However, there are some problems. One problem is unacceptable server response time when too many clients are requesting a page from the same server. In fact, when this number of clients (i.e., users) exceeds a certain threshold, often times the result is a server failure or crash. A computer crash means that the computer itself stops working or that a program aborts unexpectedly. A crash signifies either a hardware malfunction or a very serious software bug. When the response time for a server is unacceptably slow and/or has a tendency to crash often, the owner of the server may lose business. This loss of business is detrimental to a business person who mainly conducts his or her business on the Internet.
Increasing server response time to a client request may be the result of several factors. One such factor is multitasking. Multitasking, which is well known in the relevant art(s), is the ability to execute more than one task (e.g., URL or page request) at the same time. In multitasking, only one central processing unit (CPU) is involved, but it switches from one task to another so quickly that it attempts to give the appearance of executing all of the tasks at the same time. There are two basic types of multitasking: preemptive and cooperative. In preemptive multitasking, the operating system parcels out CPU time slices to each task. In cooperative multitasking, each task can control the CPU for as long as it needs it. If a task is not using the CPU, however, it can allow another task to use it temporarily. OS/2, Windows 95, Windows NT, the Amiga operating system and UNIX use preemptive multitasking, whereas Microsoft Windows 3.x and the MultiFinder (for Macintosh computers) use cooperative multitasking.
Whether the operating system of a particular server uses preemptive or cooperative multitasking, the response time to URL (page) requests increases as the number of requests increases. Under certain load conditions, these page requests can represent a considerable overhead, consuming a large percentage of the server's processing resources. What is needed is a way of guaranteeing the response time to a client's page request at a particular server (or web site), and thereby avoid wasting valuable server CUP time and crashes. In addition, what is needed is a way of providing alternative information to the user (via the client) when the server containing the desired page is not available. By providing alternative information to the user it helps to not only generate possible related business but also redirects the user back to the desired page once the server is free.